The goal of this application is to enhance the process of improving the treatment of cancer patients through cooperative clinical trials. Randomized clinical trials provide the best evidence concerning the effectiveness of different forms of therapy; consequently the National Cancer Institute (NCI) has funded clinical trials groups dedicated to developing and conducting these studies. It is now clear that, although these groups can often undertake important trials independently, in many cases cooperation among them is needed to answer key questions expeditiously. Thus, formal mechanisms for developing and conducting "intergroup" trials have been implemented and a number of such studies have been completed. The National Cancer Institute of Canada, an agency funded by donations to the Canadian Cancer Society, supports a clinical trials group (NCIC CTG) which has functions and a structure similar to US groups. Like US groups, the NCIC CTG has conducted numerous studies of its own and has made important contributions to the development of current standards of care. The NCIC CTG has also been active in intergroup trials, both as a participating and as a "lead" group. The immediate purpose of this application is to seek support for continued and enhanced participation of the NCIC CTG in US intergroup studies with the following specific aims: 1. To contribute patient enrolment, data management resources, and high quality data to intergroup trials sponsored by NCI; 2. To provide scientific input into the development design and conduct of NCI intergroup trials; and 3. To provide leadership and coordination resources for some NCI intergroup trials. Without the funding sought in this application, the NCIC CTG can, at best, make a limited contribution to the important research effort represented by intergroup trials. With it, the Group can help both in defining the questions to be addressed and in ensuring they are answered quickly and correctly.